There are few TV shows with the robots fighting each other ( https://en.wikipedia.org/wiki/Robot_combat ), but AFAIK all of them are remotely controlled. AIs are not allowed - at least these making decisions, some aiming algorithms can be used. The reason is that no one would let the machine to use at will a weapon potentially lethal to the spectators (even as simple as a blade).

On the other hand there is robot sumo, where independent AI is one if the keys to success. In Japan they try to design robotic football team, but I don't know: RC or AI. Gladiabots seems to be more like football than a real war.